Posted by: salamandercandy | March 13, 2006

Genetically modified organisms Part 1: What are they?

With the continuing advancement of the biological sciences a whole suite of technologies are rapidly developing and being implemented into modern society. One such technology, termed genetic engineering, involves the direct manipulation of genes in order to rapidly develop novel and desirable traits. The organisms that have had their DNA directly manipulated are frequently referred to as genetically modified organisms (GMOs), and less frequently as genetically engineered organisms (GEOs). Certainly, modifying plants for agricultural use is by no means a new idea. We have been continually altering plants and introducing them into novel ecosystems since the beginnings of agriculture, nearly 10,000 years ago. We have modified most crops so that they no longer scatter their seed or rely on other dispersal mechanisms apart from humans. Over numerous generations, we have selected for other desirable traits such as larger ears in corn, better flavor in tomatoes, and larger cotton bolls. In fact most crops that are widely used in agriculture today bare scant resemblance to their wild ancestors from which they were originally cultivated. Genetic modification, however, is much quicker and potentially more powerful than past agricultural manipulation, which means that there could be much greater risks involved. In this essay I would like to address the potential costs and benefits of using genetically engineered crops and how they affect consumers (e.g. health concerns), producers (e.g. economic constraints) and society as a whole (e.g. ecosystem health). I would like to explore which particular concerns are warranted and which are based on misconceptions. Lastly I would like to explore how the current and future use of GMOs will be determined by worldviews and environmental values, and how this particular issue is only a small subset of a much larger debate over modern agricultural practices.

Genetic engineering is defined as the technique of removing, modifying, or adding genes to a DNA molecule in order to change the information it contains. By changing this information, genetic engineering changes the type or amount of proteins an organism is capable of producing, thus enabling it to make new substances or perform new functions (1). For crops, this process usually involves the addition of genes that are isolated from other organisms and introduced into the plasmid of a particular bacterium. This bacterium, Argobacterium tumefaciens, is what causes crown galls in plants, which are commonly seen in trees in parks that have had branches cut off. Simply stated, this bacterium has evolved the ability to insert its DNA into the plants DNA, which then directs the plant to undergo abnormal cell proliferation causing the gall to form, and providing a source of food and habitat for the bacteria. By isolating and inserting genes for desired traits (from a wide range of organisms) into the bacterium, and then subsequently infecting the plant with the modified bacteria, we are able to insert novel genes into plants (2). The potential for creating novel organisms is vast. One of the most commonly used GM crops is Bt corn. This corn has had a gene added from a soil bacterium, Bacillus thuringiensis, which produces a protein called Bt delta endotoxin that kills the larvae of the European corn borer, a common corn pest (3). Other commonly used crops include Roundup ready soybeans and Roundup ready corn. These plants, which are patented by Monsanto, have had genes inserted into them that make them resistant to glyphosate, the active ingredient in Roundup. A farmer can therefore plant these Roundup ready crops and then spray his fields with Roundup. All plants, except for the Roundup ready crops, are killed which eliminates the need for mechanical weeding or the use of other herbicides. Other genetically modified crops include tobacco, tomatoes, potatoes, cotton and rice. Some of the stranger “creations” include inserting the gene for firefly luciferase, the enzyme responsible for light production in fireflies, into tobacco plants, which makes the plants glow in the dark ; and zebrafish with genes inserted from a sea anemone that makes them fluoresce red. With these seemingly bizarre organisms already in existence it is not surprising that there is widespread public concern.

To be continued…

2. Weaver, R.F. and P.W. Hedrick. Genetics, third edition. Wm. C. Brown Publishers (1997).



  1. […] Salamander candy (animales modificados) […]

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s


%d bloggers like this: